Scrotal cooling and its benefits to male fertility: a systematic review.

Plain-language summary

This review set out to gather what is known about whether cooling the scrotum helps sperm production. The authors searched two large medical databases, EMBASE from 1980 to 2010 and MEDLINE from 1950 to September 2010, for male fertility combined with scrotal cooling, with no limits applied. Eight studies met their criteria. The reviewers observed a positive trend towards improved male fertility with cooling, and at the same time concluded there was not enough evidence to draw any firm conclusion about it. Their reasons are about how those eight studies were built rather than about which way they pointed: all eight were small and observational, none was randomized, several ran without a comparison group, the cooling methods, the durations and the men studied differed too much to pool, the reviewers judged the risk of bias in them high, and what the studies measured was semen results rather than pregnancies or births. They called for well designed randomized controlled trials to settle it.

Key findings

• Eight studies met the criteria for inclusion.
• The reviewers observed a positive trend of improved male fertility with scrotal cooling.
• The reviewers judged the evidence insufficient to draw any firm conclusion.
• Their reasons were about how the studies were built: all eight were small and observational, none was randomized, several ran without a comparison group, and the cooling methods, durations and men studied varied too much to pool.
• What the eight studies measured was semen results rather than pregnancies or births, so the review cannot say whether cooling produces a baby.
• The reviewers called for well designed randomized controlled trials.